If matrix A=|1&2&-1 3&4&5 0&6&7| and its inverse is denoted by A-1=|a11&a12&a13 a21&a22&a23 a31&a32&a33| , then the value of a23 is

Question

If matrix A=|1&2&-1 3&4&5 0&6&7| and its inverse is denoted by A-1=|a11&a12&a13 a21&a22&a23 a31&a32&a33| , then the value of a23 is (A)  (21/20)  (B)  (1/5)  (C)  -(2/5)  (D)  (2/5)

Tardigrade Admin · Accepted Answer

|A|=-20 ∴ a23=( text Coractor /-20)=(-8/20)=(-2/5)

Q. If matrix $A = ∣ ∣ 130246 - 1 57 ∣ ∣$ and its inverse is denoted by $A^{- 1} = ∣ ∣ a_{11} a_{21} a_{31} a_{12} a_{22} a_{32} a_{13} a_{23} a_{33} ∣ ∣$ , then the value of $a_{23}$ is

$\frac{21}{20}$

$\frac{1}{5}$

$- \frac{2}{5}$

$\frac{2}{5}$

$∣ A ∣ = - 20$
$∴ a_{23} = \frac{Coractor}{- 20} = \frac{- 8}{20} = \frac{- 2}{5}$

Q. If matrix A=∣∣​130​246​−157​∣∣​ and its inverse is denoted by A−1=∣∣​a11​a21​a31​​a12​a22​a32​​a13​a23​a33​​∣∣​ , then the value of a23​ is

2021​

51​

−52​

52​